Ball-type sealing device

ABSTRACT

A ball-type sealing device is disclosed for preventing fluid flow out of an orifice wherein the sealing ball is mounted in a body member so as to have both radial or transverse and axial degrees of freedom. The sealing ball, which has a diameter greater than that of the orifice, is mounted in a chamber defined by the body member such that a portion of the ball extends through an aperture in the end of the chamber to the exterior of the body member. The sealing ball is positioned by a pushrod slidably extending into an elongated hole defined by the body member such that one end of the pushrod, having a first contact surface S 1 , is in contact with the sealing ball. The opposite end of the pushrod is associated with a second contact surface S 2  which has an area smaller than the contact surface S 1 . The sealing ball may be accurately placed in the orifice to be sealed since it has both a transverse degree of freedom, due to the diameter of the chamber in the body member being larger than the diameter of the sealing ball, as well as an axial degree of freedom. Pressure exerted on the sealing ball along the longitudinal axis of the body member exerts a force on the pushrod which, in turn, causes permanent axial deformation of a crush portion of the body member adjacent to the second end of the pushrod. This deformation provides the necessary axial play or clearance between the pushor and the ball.

BACKGROUND OF THE INVENTION

The present invention relates to a device for sealing an orifice whereina ball-type sealing device is urged against the orifice with a specificforce. The invention finds use in hydraulic, pneumatic, or mechanicalthrust devices or pistons.

In order to establish complete sealing for mechanical devices such aspushrods, pistons, valves, etc., semi-permanent or intermittent butcomplete contact must be established at the opening of a cylindricalorifice. To achieve such complete sealing, known elements were machinedwith high accuracy to provide an accurate fit between the elements.However, such known machinery elements were subject to deviation fromthe desired dimensions and were quite costly to manufacture.

Another solution to provide complete sealing is to seal the orifice withan element having one or more degrees of freedom. This enables thesealing element to match the corresponding part, such as the structuredefining the end of the orifice being sealed, so as to assure permanentand tight contact. If the sealing element were crudely placed oppositethe orifice to be sealed, it would not necessarily be centered withrespect to the orifice unless the sealing part were also able to enjoyat least one degree of freedom relative to the axis of the orifice.However, in the known devices, asymmetry of the applied stresses by thesealing part may cause lack of homogeneity in the sealing of theorifice.

SUMMARY OF THE INVENTION

A ball-type sealing device is disclosed for preventing fluid flow out ofan orifice wherein the sealing ball is mounted in a body member so as tohave both radial or transverse and axial degrees of freedom. The sealingball, which has a diameter greater than that of the orifice, is mountedin a chamber defined by the body member such that a portion of the ballextends through an aperture in the end of the chamber to the exterior ofthe body member.

The sealing ball is positioned by a pushrod slidably extending into anelongated hole defined by the body member such that one end of thepushrod, having a first contact surface S₁, is in contact with thesealing ball. The opposite end of the pushrod is associated with asecond contact surface S₂ which has an area smaller than the contactsurface S₁.

The sealing ball may be accurately placed in the orifice to be sealedsince it has both a transverse degree of freedom, due to the diameter ofthe chamber in the body member being larger than the diameter of thesealing ball, as well as an axial degree of freedom. Pressure exerted onthe sealing ball along the longitudinal axis of the body member exerts aforce on the pushrod which, in turn, causes permanent axial deformationof a crush portion of the body member adjacent to the second end of thepushrod. This deformation provides the necessary axial play or clearancebetween the pushrod and the ball. Due to both the radial or transverseand the axial degrees of freedom of the sealing ball, it may accuratelycenter itself on the orifice to effect a complete sealing without theexertion of undue stresses on the orifice structure, and without thenecessity of highly accurate and costly machining operations.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal, cross-sectional view of the ball-type sealingdevice according to the present invention before the axial play orclearance has been established.

FIG. 2 is a partial, enlarged, cross-sectional view of the inventionillustrated in FIG. 1 showing the system for implementing the axialclearance or play.

FIG. 3 is an enlarged, partial, cross-sectional view of the inventionafter the axial play or clearance has been established.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As best illustrated in FIG. 1, the ball-type sealing device 1 of theinvention is located in a support 4, which may be any means to positionthe sealing device of this invention relative to orifice 8 defined inpneumatic or hydraulic member 6.

The sealing member comprises a generally spherical sealing ball 10having a diameter D₁₀, which is applied against the end 9 of the orifice8 in order to seal the orifice to prevent the flow of fluidtherethrough. The end 9 of the orifice 8 has a diameter D₉ which is lessthan the diameter D₁₀ of the sealing ball 10. The sealing ball 10 ispositioned by a body member 2 which urges the ball against the orifice 8to be sealed. The sealing ball 10 is located within an inner chamber 12defined by the body member 2, the inner chamber 12 having a generallycylindrical configuration extending along the longitudinal axis 25 ofthe body member 2. The ends 14 of the body member 2 defining the innerchamber 12 are slightly inwardly deformed or crimped so as to preventthe sealing ball from escaping from the chamber 12. This end of the bodymember defines an aperture and, as can be clearly seen in the figures, aportion of the sealing ball 10 extends through this aperture exteriorlyof the body member 2. It is this exterior portion that is urged againstthe opening of orifice 8 to effect the seal.

Body member 2 is slidably mounted in support 4 such that a force K,illustrated in FIG. 1, applied to the body 2 is transferred to thesealing ball 10 so as to urge it against the orifice 8. Force K may, ofcourse, be generated by pneumatic, hydraulic or mechanical means.

In order to establish complete, hermetic sealing of the end 9 of theorifice 8, the sealing ball 10 must have at least one operational degreeof freedom. If the body member 2 positioned by the support 4 were toplace the sealing ball 10 against the orifice 8 such that it wasnon-axially located, then the sealing ball 10 could not hermeticallyseal the orifice 8. In that particular instance, the sealing ball 10would rest only on a portion of the circumference of the end 9 of theorifice 8. Thus, the sealing ball would be asymmetrically forced againstthe structure defining the orifice 8 resulting in premature andasymmetric wear of the sealing ball. Experience has shown, therefore,that a radial or a transverse clearance between the sealing ball 10 andthe part with which it is associated is required in the event that bodymember 2 and the orifice 8 are offset so that the sealing ball cancenter itself in the orifice 8.

In addition, an axial play or clearance is required to keep the sealingball 10 in position by means of the crimped ends 14. In the presentinvention, the axial play or clearance is independent of the radial ortransverse play or clearance such that both can be adjusted autonomouslyduring the operation of the sealing device. The axial play or clearanceis achieved by means of a pushrod 16 which is slidably received in anelongated opening 26 defined by the body member 2. The pushrod has afirst end 21 defining a first contact surface S₁ which is in contactwith the sealing ball 10. A second end 22 of the pushrod 16 isoperatively associated with a crush portion of the body 2 having asecond contact surface S₂ of much lesser area than that of first contactsurface S₁. As a result, a pressure P applied against the sealing ball10 by fluid in the orifice 8 will transmit a force F to the pushrod 16through the sealing ball 10. Force F is proportional to the pressure Ptimes the area of first contact surface S₁. Force F is then transmittedto the crush portion of the body member 2 and will exert a pressurethereon P₂ which is equal force F divided by the area of the secondcontact surface S₂. Quite obviously, the force transmitted to the crushportion will vary as the ratio S₁ /S₂.

Due to the force F, the crush portion may undergo a permanentdeformation caused by the pressure on the sealing ball 10. The permanentdeformation may be controlled and predetermined so as to control, inturn, the penetration of the pushrod 16 into the crush portion of thebody member 2. In this manner, the axial play or clearance J_(A) of thesealing ball 10 inside the chamber 12 can be set in a specified manner.

In the embodiment illustrated in FIGS. 1 and 2, the second end 22 of thepushrod 16 does not directly act on the crush portion of the body member2. An intermediate deforming ball 20 is operatively interposed betweenthe second end 22 of the pushrod 16 and the second contact surface S₂ ofthe body member 2.

As best seen in FIG. 2. the contact surface S₂ is defined between thediameter of elongated opening 26 and a further extended opening 24 whichextends along longitudinal axis 25. Thus, the second contact surface S₂consists of an annulus which rests against the deforming ball 20.

In FIG. 2. the deforming ball 20 is illustrated in solid lines in itsposition following the deformation of the crush portion of the bodymember 2. Accordingly, the second contact surface S₂ assumes the shapeof a spherical annulus in the body member 2. The deformation or crushingE caused by the deforming ball 20 of the body member 2 depends upon theforce F exerted thereon by the second end 22 of pushrod 16. The axialplay or clearance J_(A) is proportional to this crushing or deformationE as a function of the angle between the second contact surface S₂ andthe longitudinal axis 25 on which the deforming ball 20 is located andwhich also constitutes the axis of the elongated hole 26.

In FIG. 3, the axial play or clearance J_(A) is shown near the firstcontact surface S₁. The axial play or clearnce J_(A) was achieved by athrust on the sealing ball 10 once it had been put in place within theinner chamber 12 and after the radial play or clearance J_(R) was set.It is mandatory to first adjust the radial play or clearance J_(R) bymilling or otherwise forming the internal chamber 12 to a diameter D₁₂which is slightly larger than the diameter D₁₀ of the sealing ball 10.Thus, the radial play or clearance J_(R) is established by thedifference between D₁₂ and D₁₀.

Once the sealing ball 10 has been introduced into the inner chamber 12,the end 14 of the body member 2 is slightly crimped so as to create anaperture having a diameter of D₀ which is less than the diameter D₁₀ ofthe sealing ball so as to retain the sealing ball in the inner chamber12. At this point, the ball is in the position shown by dashed lines inFIG. 3. The axial play J_(A) can then be established as discussed above,by applying a specified pressure against the sealing ball 10 so as tocause permanent deformation of the crush portion of the body member 2.Once this has been accomplished, the sealing device has a sealing ballwhich has both radial or transverse, as well as axial degrees offreedom.

Accordingly, the magnitude of the axial play J_(A) depends upon thefollowing parameters:

a) the pressure P exerted on the sealing ball 10;

b) the area of the first contact surface S₁ ;

c) the area of the second contact surface S₂ ;

d) the eccentricity of the second contact surface S₂ ; and

e) the respective hardnesses of the sealing ball 10, the pushrod 16, thedeforming ball 20 and the body member 2.

Clearly, the independent establishment of the radial or transverse playJ_(R) and the axial play or clearance J_(A) allows the sealing device tobe used in many varieties of operations, each of which may requiredifferent operational parameters. Regardless of the operatingparameters, the contact between the sealing ball 10 and the end 9 of theorifice 8 will be optimal resulting in zero lateral or transversestresses at the contact area.

The foregoing description is provided for illustrative purposes only andshould not be construed as in any way limiting this invention, the scopeof which is defined solely by the appended claims.

We claim:
 1. A ball-type sealing device for preventing fluid flow out ofan orifice having a diameter D₉ comprising:a) a body member having alongitudinal axis and defining an inner chamber with an end portiondefining an aperature communicating with the inner chamber, the chamberhaving a generally cylindrical configuration extending along thelongitudinal axis with a transverse diameter D₁₂. b) a sealing balloperatively retained in the inner chamber, the sealing ball having asubstantially spherical shape with a diameter D₁₀ such that D₁₀ >D₉ andsuch that D₁₀ <D₁₂, so as to define a radial clearance between thesealing ball and the body member thereby permitting relative transversemovement between the sealing ball and the body member; and, c) meanspositioning the sealing ball such that a portion of the sealing ballextends through the aperture exteriorly of the body member to seal theorifice and permitting movement of the sealing ball relative to the bodymember in both a radial direction generally transverse to thelongitudinal axis of the body member and an axial direction generallyparallel to the longitudinal axis, the means comprising: i) a pushrodslidably received in an elongated hole defined by the body member, thepushrod having a first end defining a first contact surface S₁ incontact with the sealing ball and a second end; and,ii) a crush portiondefined by the body member in operative association with the second endof the pushrod, the crush portion having a second contact surface S₂having an area smaller than the first contact surface S₁ such that apredetermined pressure exerted on the sealing ball causes permanentaxial deformation of the crush portion to establish an axial operationalclearance.
 2. The ball-type sealing service of claim 1 furthercomprising a deforming ball operatively interposed between the crushportion and the second end of the pushrod.
 3. The ball-type sealingdevice of claim 2 wherein the second contact surface has an annularconfiguration.